Figure 1.

Activity-dependent EPSC decrease in the absence of glutamate. A, Sampled presynaptic calcium currents (ICa), EPSCs, and presynaptic C_m induced by the first, sixth, and 10th Train_1Hz applied every 30 s. The rate of C_m decay (Rate_decay) in the interval between each 20 ms depolarization during Train_1Hz is also plotted. The presynaptic pipette contained 0 mm glutamate (Glu applies to A–G). B, ICa, EPSC, and C_m induced by the first 20 ms depolarization during first (black), sixth (blue), and 10th (red) Train_1Hz shown in A are superimposed. C–E, The QICa, ΔC_m, and QEPSC induced by each Train_1Hz are plotted versus the number of Train_1Hz applied every 30 s (C, n = 8), 60 s (D, n = 8), or 300 s (E, n = 5). Data were normalized to the amplitude (Amp) induced by the first Train_1Hz, and expressed as the mean ± SEM (applied to all figures). F, QEPSC in C and D are plotted versus the Train_1Hz number. G, The mean mEPSC amplitude recorded between Train_1Hz applied every 30 s for 15 times (n = 4 synapses, no kynurenic acid in bath).